>>101260453Psychedelics can absolutely exacerbate and kickstart mental illness, including schizophrenia, and can induce psychosis (usually temporary, rarely it can be long lasting and even permanent. It's well documented and can even happen with weed, although I've never heard of that happening myself. I do have first hand knowledge of this happening with both LSD and mushrooms.
With the LSD, it wasn't even his first trip, nor his strongest. 2 mid-low strength hits and he lost it, started wandering the streets, ended up in jail which didn't help, even after it was all out of his system he wasn't really back, he was never the same again. Even three years out he's normalized a bit but he's not really any closer to who he used to be (this isn't like he reinvented himself after a really introspective trip, there wasn't any choice in the matter and it was not a positive thing for him or his friends/family).
The mushrooms thing I don't know the guy, patient of a friend. Did some mushrooms in amsterdam and had a psychotic break, now he has that happen sometimes. Whether these things would have developed on their own is anyone's guess at the moment, and I don't know anything about Sim's mental health history or drug use.